A number of apparatuses have been devised in the prior art to address the problem of oil spills that affect large bodies of water such as oceans and lakes. Such oil spills may be the result of accidental release of hydrocarbons from a line leakages from multitude of motorboats, or of large ocean going oil tanker vessels that run aground and with their hull rupturing and thus releasing to the environment their biotoxic content. Since oil has a lower specific density than water, it will automatically rise to the top of the contaminated body of water, and will remain so as a surface oil film. Therefore, the prior art oil decontamination apparatuses are usually directed at collecting the surface liquid film from the body of water, and proceeding afterwards to a gravity phase separation of oil and water inside separation chambers, so as to separate the two components into an oil rich solution and a water rich solution. These two separated solutions can then be further processed for possible economic reclaiming, or at least for meeting environmental regulations that enable authorized release to the environment of the water rich solution and reuse of the oil rich solution for low grade economic oil applications.
An example of such an apparatus is U.S. Pat. No. 5,527,461 issued in June 1996 to the Canadian Gordon Hill, discloses an apparatus for separating an oil film from a body of water on which it is floating. The apparatus comprises a main inner chamber having an inlet in register with the surface of the contaminated body of water. A riser is mounted centrally of the main chamber, having a bottom mouth spaced from the main chamber flooring. Vertical baffles extend around the riser inside the main chamber. The contaminated water enters the main chamber and the oil and water components thereof are subjected to a preliminary gravity separation due to their differential densities. The baffles enhances this gravity separation of the oil from the water, by first directing the flow down toward the mouth of the riser, and then directing the flow upward to a second separation zone, and finally downwards once again to the entrance of the riser. A bottom compressed air nozzle is thus provided beneath the bottom mouth of the riser, for injecting gas bubbles into the apparatus so that small slugs of oil in the water are attracted to and become attached to the air bubbles. At the surface of the riser, the bubbles burst and the oil is released to agglomerate with the other slugs being released at the top. The oil, water and slurry at the top of the riser is withdrawn through an outlet port at the top of the riser. The thick layer of oil having accumulated over the body of water inside the main chamber, is removed therefrom using oil recovery lines having their oil intakes positioned at the oil layer surface.
There are two major problems with such an oil spill treatment apparatus:
a) it does not appear possible to prevent at least some water from the top oil rich layer inside the apparatus main chamber, from engaging into the oil recovery lines, since the physical interface between this oil rich layer and the underlying body of water is not clear cut. A progressively increasing proportion of water will be found in this top oil layer as the oil layer is progressively depleted by suction action of the oil recovery lines.
b) it would not further appear possible to stop the suction action of the oil recovery lines, when the oil rich layer has been totally removed from the main chamber, otherwise than manually by an operator continuously inspecting the situation via sensors positioned inside the apparatus. No means for automatically shutting off operation of the oil recovery lines appear possible in this type of system, when the oil spill has been clean-up, thus reducing the economical value of the collected oil.
Accordingly, economic reclaiming of the oil component from the contaminated body body of water, would not appear to be efficiently carried out in prior art oil spill cleanup apparatuses.
Some of these prior art oil spill clean-up apparatus references also make use of the communicating vessels principle in enhancing the gravity separation of the oil from the water through tubes interconnecting two separate chambers: see for example U.S. Pat. No. 5,560,826 issued in October 1996 to the Hungarians Szereday and Toth.
Furthermore, many of these prior art references require on board motor driven propellors, in view of moving the apparatus about the water and/or to enable water and oil flow through the apparatus for drawing in the contaminated water surrounding the apparatus; these high speed propellers are safety hazards for maintenance crews. Some however do provide for safer compressed air lines that generate air bubbles, to continuously maintain a suction induced contaminated water flow through the apparatus from the large body of water: see for example the Hill patent, supra.